Tweak kick-out condition K2b to deal with LHSs
Commit message:
Tweak kick-out condition K2b to deal with LHSs
Kick out condition K2b really only makes sense for
inerts with a type variable on the left. This updates
the commentary and the code to skip this check for
inerts with type families on the left.
Close #19042.
test case: typecheck/should_compile/T19042
Tag #19042 (closed).